Coupled bending-torsional vibration of a cracked hollow beam model in water and identification of cracking

The coupled flexural-torsional vibration equations of a floating beam model, considering added fluid masses, are developed. The beam has varying bending stiffness, varying torsional stiffness and varying mass distribution; frequencies and mode shapes are calculated using Galerkin's method. Stiffness for the cracked beam (backbone) has been calculated using an energy procedure. Experimental values have been compared with the results of theoretical predictions and the agreement between the two found to be good. The frequency contour method has been used to identify the crack.